Field of the Invention
The present invention relates generally to devices and methods for ligating body structures and, more particularly, to devices and methods for positioning a preformed ligating loop around the body structure, tightening the loop, and severing the loop from the device, where the user need only perform a single motion with the device.
Pre-tied ligating loops are utilized in surgical procedures for a variety of purposes. Most commonly, the ligating loops will be placed around the outside of a severed body lumen, such as a blood vessel or the cystic duct, tightened by pulling on a free end of the ligature, and severed, typically using separate severing shears. Often, the ligating loop will be mounted at the end of a rod or tube so that the surgeon may push on the knot with the tube while pulling on the free end of the ligature to tighten the loop.
While relatively easy to perform in open surgical procedures, the application, tightening, and cutting of pre-tied ligating loops is more problematic in laparoscopic and endoscopic procedures where the loop must be introduced and manipulated through a small incision, narrow trocar sleeve, or the like, while the surgeon views the procedure through an electronic imaging system. While the use of a pusher rod or tube facilitates such laparoscopic and endoscopic procedures somewhat, it is still necessary to sever the loop from the free end of the ligature after tightening. Generally, this has required the introduction of a separate cutting device, usually through a second incision or trocar sleeve.
For these reasons, it be desirable to provide improved devices and methods for applying pre-tied ligating loops to body structures, where the application, tightening, and severing steps described above can be performed using a single instrument. It would be particularly desirable if the single instrument could be manipulated using one hand and if the steps of tightening and severing the ligating loop could be performed with a single motion of the hand. Such methods and devices should be suitable for open surgical procedures as well as for laparoscopic and endoscopic procedures, and should automatically provide for an appropriate degree of tightening of the pre-tied knot as the ligating loop is being tightened prior to severing.